Planar Knowledge and Hierarchical Skills

Planar Knowledge and Hierarchical Skills

Here's a fairly simple system change to the problem of Planescape's multitudinous and multifarious Knowledge (planes) skills. Don't be put off by the terminology; I'm trying to create a skill-hierarchy system that's flexible enough to be used for other skill sets, too. Comments, criticisms, complaints, carps, cavils and conks upon the cranium would all be appreciated.

Hierarchy: Knowledge (planes)

The hierarchy is represented by a (finitely-branching?) tree with root "Knowledge (planes)". Each successive level represents a specialization of this knowledge to some facet of the planes. I'll use tree vocabulary when describing this (although a picture would be so much better, I've no doubt); hence a node means something like Knowledge (Planes|Outer Planes) and its daughter nodes (or children) would be nodes like (Planes|Outer Planes/Mt Celestia), (Planes|Outer Planes/Bytopia), and so on.

• Level 0: Knowledge (Planes)
• Level 1: Outer Planes, Inner Planes, Transitive Planes, Prime Material Planes, Obscura
• Level 2, Outer Planes: All 17 Outer Planes + Sigil (due to the latter's primacy in Outer Planar Dealings)
• Level 2, IP: All Inner Planes
• Level 2, TP: Astral, Ethereal, Shadow, Ordial (if it exists), all Planar Pathways*
• Level 2, PMP: All Primes.
• Level 2, Obscura: no subclasses. Generic repository of "Planar Mysteries", e.g. how did Vecna escape the Dark Domains, what are the baernaloths, what lies beneath the sands of Pelion, etc. See below.
• Further subclassing is possible although not particularly encouraged for PCs, e.g. having Knowledge (Planes|Outer Planes/Baator/Minauros/Jangling Hiter) or Knowledge (Planes|Transitive Planes/Ethereal/Demiplane of Neph)

Nodes will be described, for ASCII-related purposes, as:

([Level 0] | [Level 1] / [Level 2] / ...)

* Option: At the DM's discretion, Planar Pathways that lie entirely within the confines of another node in the hierarchy, e.g. the Styx lying entirely within the Outer Planes, may be classed under both Transitive and the relevant node. Conversely, Planar Pathways can simply be eliminated wholesale, moved up to level 1, or whatever you think is appropriate.

Remark: Being a logician, trees for me always go down. This means that I regard (Planes|Outer Planes/Mechanus) as a lower node than (Planes|Outer Planes). Many other disciplines regard trees as going up, so level 2 would be a higher level than level 1. To try and avoid this confusion, I'm using "deeper" to mean "deeper into the tree, i.e. at a higher level than another node.

Ranks

When choosing where to place skill ranks, a PC must choose a particular node within the hierarchy for each point. If the PC wants to put 3 ranks into Knowledge (planes), she could choose to put 2 into Outer Planes (P|OP) and 1 into the Negative Material Plane (P|IP/NMP).

Optional: It is assumed that any class that currently has Knowledge (planes) listed as a class skill will have the entirety of the hierarchy as a class skill, and likewise that the entire hierarchy will remain cross-class if the class does not. This can be modified at one's discretion, especially in the case of, say, elemental PrCs.

Hierarchical and Synergy Bonuses

For every 3 ranks in a particular node in the hierarchy, all children nodes receive a +1 hierarchical bonus. 7 ranks in Knowledge (Planes), for example, would grant the character a +2 bonus to all checks made in Knowledge (Planes|Outer Planes), (Planes|Inner Planes) and so forth.

Unless explicitly stated otherwise -- i.e. unless the DM explicitly declares otherwise -- all 3.x Knowledge (planes) synergy bonuses, whether gained or given by Knowledge (planes), apply to the root of the hierarchy only.

Skill checks

To determine which part of the hierarchy is appropriate for a given skill check, the following two determinations must be made:

• What is the deepest level of the hierarchy at which such a question can be meaningfully asked?
• What is the DC of that question asked within those parameters?

For example, suppose the party is on the Plane of Fire and wishes to know if they're near the City of Brass. The DM rules that this is properly within the domain of Knowledge (Planes|Inner Planes/Fire) and, in that domain, is DC 15.

When attempting the skill check, the character may either:

• Make the check against that DC with their skill in that particular node
• Make the check against that DC +5 with their skill in the parent node (i.e. jump one level up in the hierarchy at the cost of a -5 penalty)
• Make the check against that DC +10 with their skill in the parent's parent's node, if such exists (i.e. jump two levels up the hierarchy at the cost of a -10 penalty).

To illustrate this, consider the above example -- a DC 15 check in (P|IP/F) -- with the following three characters (about whom I make no claims to realism):

• Bekah, Knowledge (P): +2, (P|IP): +2, (P|IP/F): +2
• Kahrl, Knowledge (P): +1, (P|IP): +10, (P|IP/F): +3
• X'sisto, Knowledge (P): +20 (P|IP): +7, (P|IP/F): +1

Bekah would clearly be best-served by trying the DC 15 check in (P|IP/F) where she has +2. Kahrl, whose real specialty is in the Plane of Air, would be best-served by trying the DC 20 check in (P|IP) where he has a +10 bonus [where he succeeds on 10 or higher], rather than the specific check of DC 15 in (P|IP/F) where he has only a +2 bonus [where he only succeeds on 13 or higher]. X'sisto, the Outer Planar generalist, should attempt the check on (P) where his +20 bonus will serve him well against the DC 25 check.

Optional rules

1. Allow checks more levels up in the hierarchy, imposing a -5 for each level further up. Hence one could transform a DC 15 check in (Planes|Outer Planes/Baator/Minauros/Jangling Hiter) to a DC 35 check in (Planes)
2. Disallow moves up the hierarchy if the new DC is greater than 25 (or even 20): the knowledge is simply too specialized. Hence one could turn a DC 20 Knowledge (P|IP/W) check into a DC 25 Knowledge (P|IP) check but not a DC 30 Knowledge (P) check.
3. 5 ranks at a node of level 2 or deeper grants a +2 synergy bonus for all other siblings of that node. Thus, for example, 5 ranks in (P|OP/Mt Celestia) would grant a +2 synergy bonus to all other outer planar knowledge checks.
4. Reverse synergy: 10 ranks or more in a child node grants a +2 synergy bonus to the parent node. Thus, for example, 10 ranks in (P|TP/Astral) would grant a +2 synergy bonus to (P|Transitive Planes). These bonuses stack for each child.
5. Currently, the hierarchy bonus is +1/3 ranks. It might make more sense for it to be +1/3 (rank + hierarchy bonus). That is, if you have 10 ranks in (P) and 6 ranks in (P|IP), your hierarchy bonus for (P|IP/Vacuum) should be +3 [6 ranks in (P|IP) plus +3 hierarchy bonus from the 10 ranks in (P)] rather than +2 [for just the 6 ranks in (P|IP)]. Another way to look at it would be that the hierarchy bonus is +1/3 ranks of the parent skill and +1/9 ranks of the grandparent skill, assuming no-one's running around with 27 ranks of Knowledge.
6. As I've been doing above, Knowledge (local) for planar locations can be subsumed into the hierarchy if you so desire.
7. Conversely, well-known locations can be considered elevated one level in the hierarchy as I've done with Sigil. The City of Brass, for example, may be so important in your campaign that it's actually considered a daughter of Inner Planes, not Plane of Fire; or possibly it's even considered both, gaining the hierarchy bonuses from both your ranks in Inner Planes and your ranks in Plane of Fire. If the latter route is chosen, the same should be true of Sigil: it should simultaneously be considered a child of both Outer Planes and The Outlands.
8. One could also try a complicated thing where skill points placed further down the tree "count for less" in some way, but I think the various synergies and hierarchy bonuses accommodate this.

Knowledge (planar/Obscura)

This is pretty much an optional rule too -- feel free to exclude it if you like -- in that where the other planar categories are basically disjoint, Obscura overlaps everything. Essentially, anything that might be a piece of trivia, a legend, anything like that is covered in this category. Typical Obscura-style questions would be:

• How did Vecna escape the Dark Domains?
• What the baernaloths?
• What lies beneath the sands of Pelion?
• What happened to Orcus?
• Who's the Lady of Pain?
• What's in the middle of the Negative Material Plane?
• Is there any way to get from the Beastlands to Carceri without travelling through any other Outer Planes?

If successful, the check will either provide appropriate rumors -- Vecna's a bad-ass, the baernaloths are puppetmasters, the Lady's six giant squirrels with a ring of levitation -- or, if it makes sense, actual knowledge of the event. Think of it as sort of Knowledge ({planar} legends) for the whole of the Planes.

I haven't offered any DCs here because it's dependent on what your characters know, where they've been, what's happened in your campaign, and so forth. In general, I'd suggest using the bardic knowledge DCs for this kind of thing; the one restriction is that the DC of an Obscura check should never be less than the DC for the Knowledge check in the relevant area.

SUMMARY

• Knowledge (planes) is now represented as a hierarchy -- a tree, to be precise -- of related skills. The levels of this hierarchy are fairly granular; they run something like [type of plane] -> [plane] -> [layer] -> [major location].
• Each skill gives a +1 hierarchy bonus per 3 ranks to all its daughter skills.
• The DC of a check is determined by the DC in the domain of its deepest relevant skill. Checks may be made at higher nodes at the cost of a +5 penalty to DC.
• Knowledge (planes|Obscura) functions as a hybrid of bardic knowledge and Knowledge ({planar} legends).